Page URL:

Male chromosome not dying out, say researchers

13 January 2014
Appeared in BioNews 737

The human Y chromosome may have some use, after all. Experts previously thought that the chromosome containing 'male' genes was shrinking to the point of extinction.

A study published in PLOS Genetics suggests that natural selection may be maintaining genes on the Y chromosome. This chromosome 'tells' an embryo to develop biologically male characteristics. Many of the tiny Y's 27 genes are linked to male fertility.

Most chromosomes come in pairs and swap DNA when cells divide into sex cells – a process known as recombination. The Y chromosome, however, has no genetic partner. Researchers think this can lead to damage from harmful mutations building up over time. This may cause DNA to be discarded and the chromosome to dwindle.

'The Y chromosome has lost 90 percent of the genes it once shared with the female X chromosome, and some scientists have speculated that the Y chromosome will disappear in less than five million years', said Dr Melissa Wilson Sayres, an evolutionary biologist from the University of California, Berkeley and lead author of the study.

'Our study demonstrates that the genes that have been maintained, and those that migrated from the X to the Y, are important, and the human Y is going to stick around for a long while'.

The researchers analysed the complete genomes of 16 men – eight from Africa, eight from Europe. They found that Y chromosome variation between the men was very small, suggesting a 'purifying' form of natural selection has whittled it down to the bare necessities.

The continued existence of the 27 Y chromosomes genes may mean they play a vital role. Seventeen of these genes have remained intact after 200 million years of evolution. The other ten, called ampliconic genes, were more recently acquired.

According to Dr Wilson Sayres: 'These ampliconic regions that we haven’t really understood until now are evidently very important and probably should be investigated and studied for fertility'.

A common alternative explanation for the lack of Y chromosome variation in humans is that relatively few men fathered a disproportionate number of children. This is popularly known as the 'Genghis Khan effect', after the Mongol leader whose Y chromosome can still be found in 0.5 percent of males worldwide.

The study demonstrated that if this explanation were true, fewer than one in four males could have passed on their Y chromosomes to future generations.

Male Y chromosome 'is here to stay'
MSN News |  10 January 2014
Men are here to stay: DNA analysis reveals that the Y chromosome is not dying out
Mail Online |  10 January 2014
Natural Selection Reduced Diversity on Human Y Chromosomes
PLOS Genetics |  9 January 2014
The human Y chromosome is not likely to disappear
EurekAlert! (press release) |  9 January 2014
Y chromosome is not doomed to shrivel away to nothing, say researchers
The Guardian |  9 January 2014
7 March 2016 - by Dr Katie Howe 
A new DNA-sequencing method has been developed, which has been used to determine the sequence of the gorilla Y chromosome...
26 May 2015 - by Natalie Moska 
Last week I attended a Pint of Science session entitled 'Sugar and Sperm' held at a floating pub on Albert Embankment in London - part of a worldwide festival hosting more than 600 evenings of science in 50 cities and eight countries as far afield as Australia and the USA...
23 February 2015 - by Sophie McLachlan 
Humanity's predisposition to disease has been reduced thanks to hundreds of generations of sexual reproduction, research shows...
15 December 2014 - by Arit Udoh 
Smoking can accelerate the loss of the Y chromosome in blood cells, a study claims...
29 September 2014 - by Dr Victoria Burchell 
The rise of the single mother may seem a rather modern phenomenon. But even before the first humans walked out of Africa 70,000 years ago, mothers have consistently outnumbered fathers, DNA analysis suggests...
25 November 2013 - by Dr Naqash Raja 
Male mice are able to reproduce healthy offspring with only two Y-chromosome genes, researchers at the University of Hawaii have discovered...
29 July 2013 - by Clara Salice 
The 'female' X chromosome has been shown to contain several genes that may be involved in sperm production...
27 February 2012 - by Ruth Saunders 
Men may not be on the brink of extinction after all, according to a study on the evolution of the human Y chromosome. Previous research has suggested that the Y sex chromosome, carried only by men, is decaying genetically at such a rate that men would become extinct in five million years' time...
18 January 2010 - by Rose Palmer 
Scientists have found that the Y chromosome is evolving more quickly than any other part of the human genetic code. In the first comparison of human and chimpanzee Y chromosomes, a team from the Whitehead Institute, Massachusetts, US, found that the two differ dramatically in structure and gene content. The finding was published in the journal Nature....
to add a Comment.

By posting a comment you agree to abide by the BioNews terms and conditions

Syndicate this story - click here to enquire about using this story.